Trigger Travel Stop Limit

ABSTRACT

A firearm trigger assembly has a trigger housing including a first opening and second opening through a surface of the trigger housing. A trigger assembly is disposed partially within the trigger housing. The trigger assembly has a trigger body with a trigger pull disposed within the trigger housing, disconnector in contact with the trigger body, and hammer body rotationally connected to the trigger body and latchable to the trigger body. A first limit stop, such as a first set screw, is disposed through the first opening and contacts the trigger body to stop movement of the trigger assembly in the first direction, and a second limit stop, such as a second set screw, is disposed through the second opening and contacts the trigger body to stop movement of the trigger assembly in the second direction. The trigger body has a concave surface adapted to receive a safety selector.

CLAIM OF DOMESTIC PRIORITY

The present application claims the benefit of U.S. Provisional Application No. 63/134,935, filed Jan. 7, 2021, which application is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates in general to firearms and, more particularly, to a firearm and method of limiting travel of the trigger assembly by using limit stops.

BACKGROUND

Modern firearms are designed and manufactured to operate with multiple inter-operational components and often with modular construction. In one example, an AR-10 or AR-15 style sporting rifle 100 uses a modular construction with an upper receiver 102 and lower receiver 104, as shown in FIG. 1 a. Lower receiver 104 is characterized by trigger guard 106, trigger assembly 108, pistol grip 110, and magazine well 112. Buttstock 114 attaches to lower receiver 104. Upper receiver 102 is characterized by bolt carrier assembly, forward assist, charging handle, and gas-operated reloader. Barrel assembly 120 with handguard 122 attaches to upper receiver 102. Lower receiver 104 is attached to upper receiver 102 by removable rear take-down pin 124 and forward pivot pin 126. Removing rear take-down pin 124 allows upper receiver 102 to hinge and rotate about forward pivot pin 126, see FIG. 1 b.

The AR-10 and AR-15 platforms typically use a drop-in type trigger assembly. The trigger assembly includes a trigger housing, trigger body, disconnector, and hammer body. The trigger body includes an integral trigger pull and fits in and through the trigger housing. The disconnector is attached to the trigger body and inhibits automatic operation of the firearm. The trigger body engages a sear or notch in the hammer body to hold the trigger assembly in a cocked position, ready to fire. Upon applying pressure to the trigger pull, the trigger body releases or breaks from the hammer sear. The hammer body strikes the fire pin to discharge the weapon.

There is typically pre-travel or take-up, creep travel, and post-travel or over-travel in the trigger pull. In some contexts, creep travel is considered part of pre-travel, but in the interest of clarity, creep travel will be considered separately from pre-travel. Pre-travel is that movement for the trigger pull to bring the trigger body in pressure contact with the sear, up to the wall without releasing the hammer body. Creep travel is that movement of the trigger pull necessary to cause movement in the trigger body, breaking the wall and releasing the hammer to discharge the firearm. Post-travel is that movement of the trigger pull after discharge of the firearm. Pre-travel play and post-travel play can each be in the range of 0.15 to 0.32 centimeters (cm). With pre-travel and post-travel, the trigger pull and trigger body travel further than is actually necessary to release the hammer. The amount of pre-travel and post-travel is typically controlled using springs and generally follows the quality of the trigger assembly, i.e., high quality components tend to have less pre-travel and post-travel. Another method of reducing pre-travel is to reduce the trigger pull pressure, generally stated in terms of pounds of trigger pull, needed to break the wall and discharge the firearm. However, reducing trigger pressure tends to make the weapon susceptible to unintentional discharge, which is a major safety concern. Nonetheless, with pre-travel, the trigger pull travels further than necessary to reach creep travel. Pre-travel and post-travel cause undesired movement in the trigger and for the weapon as a whole. Shooting accuracy is reduced with excessive movement, as well as reliability in firing the weapon.

BRIEF DESCRIPTION OF THE DRAWING

FIGS. 1a-1b illustrate a sporting rifle with conventional upper receiver, lower receiver, and trigger assembly;

FIGS. 2a-2b illustrate a sporting rifle with an upper receiver, lower receiver, and improved trigger assembly;

FIGS. 3a-3n illustrate the improved trigger assembly with a travel limit set screw and hammer limit set screw;

FIG. 4 illustrates implementing limit stops as solid shafts; and

FIGS. 5a-5e illustrate the safety selector operating with the trigger body.

DETAILED DESCRIPTION OF THE DRAWINGS

The following describes one or more embodiments with reference to the figures, in which like numerals represent the same or similar elements. While the figures are described in terms of the best mode for achieving certain objectives, the description is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the disclosure.

FIG. 2a shows an AR-10 or AR-15 style sporting rifle 200 designed for modular construction and manufactured for interchangeability of components. Sporting rifle 200 has upper receiver 202, typically forged or casted then computer numerical control (CNC) machined, and lower receiver 204, typically forged or casted then CNC machined. Lower receiver 204 includes trigger guard 206, trigger assembly 208, pistol grip 210, and magazine well 212. Buttstock 214 attaches to lower receiver 204. Upper receiver 202 includes bolt carrier assembly, forward assist, charging handle, and gas-operated reloader. Barrel assembly 220 with handguard 222 attaches to upper receiver 202. Lower receiver 204 is attached to upper receiver 202 by removable rear take-down pin 224 and forward pivot pin 226. Removing rear take-down pin 224 allows upper receiver 202 to hinge and rotate about forward pivot pin 226, see FIG. 2b .

FIG. 3a illustrates an exploded view of lower receiver 204 and trigger assembly 208, including trigger housing 230 and trigger assembly 232. As a feature of sporting rifle 200, trigger housing 230 and trigger assembly 232 use a travel limit set screw and hammer limit set screw to reduce or eliminate pre-travel and post-travel of the trigger pull.

FIG. 3b illustrates trigger housing 230 in isolation with slot 236 extending from surface 238 to surface 240. Slot 244 is wider than slot 236 and extends from surface 238 to surface 240. The combination of slot 236 and slot 244 will contain trigger assembly 232. A rectangular opening 250, with optional beveled edges and curved corners, is formed in surface 252 to receive trigger pull 284 of trigger body 280. Slot 236, slot 244, and well 250 can be formed by CNC machining, sinker electrical discharge machining (EDM), and laser cutting. Threaded openings 256 and 258 are formed through surface 252 and receive column set screws to hold trigger housing 280 in place within lower receiver 204. Threaded openings 260 and 262 are formed through surface 252 and extend to slot 236. In one embodiment, threaded opening 260 and 262 are 0.635 cm in diameter and formed by tapping into surface 252 of trigger housing 232. Circular openings 266 and 268 are formed through surface 270 and extend across slots 236 and 244 to exit corresponding openings in surface 272. Circular openings 266 and 268 receive pins to permit movement of the trigger pull of trigger assembly 232 and hammer body 318 to strike the firing pin, respectively.

FIG. 3c shows trigger housing 230 from an opposing orientation with slot 236 extending from surface 238 to surface 240, and slot 244 wider than slot 236 and extending from surface 238 to surface 240. Rectangular opening 250, with optional beveled edges and curved corners, is formed in surface 252 to receive trigger pull 284 of trigger body 280. Threaded openings 256 and 258 are formed through surface 252 and cut partially into surface 276. Threaded openings 260 and 262 are formed through surface 252 and extend to slot 236. Circular openings 266 and 268 are formed through surface 270 and extend across slots 236 and 244 to exit corresponding openings in surface 272. Circular openings 266 and 268 receive pins to permit movement of trigger assembly 232 and hammer body 318 to strike the firing pin.

FIG. 3d illustrates further detail of trigger assembly 232 including trigger body 280 with trigger pull 284 extending as a unitary portion of the trigger body. Trigger housing 232 and trigger assembly 232 can be applied to all drop-in trigger type firearms. Trigger shaft 286 extends through trigger body 280. Trigger body 280 has notch 288 with concave surface 290 configured to accept a safety selector. Disconnector body 294 with locking neck 296 is held in place over trigger body 280 with rounded bar 297 disposed in rounded slot 299. Disconnector spring 298 is disposed in opening 300 of disconnector body 294 and applies pressure to the bottom of the disconnector. Disconnector adjustment set screw 304 is screwed into threaded opening 306 in disconnector body 294. Disconnector adjustment lock nut 308 is threaded onto disconnector adjustment set screw 304. Trigger pull spring 310 is disposed within opening 312. Trigger pull adjustment screw 314 sets the tension on trigger pull spring 310. Hammer body 318 rotates with respect to trigger body 294 via hammer shaft 320 under tension from hammer spring 322. Hammer spring 322 is a U-shaped spring, also known as dog spring.

In FIG. 3e , trigger body 280 latchably engages with sear 334 to hold hammer body 318 under tension from hammer spring 322 when trigger assembly 232 is in a cocked position or ready to fire. That is, edge 344 of trigger body 280 engages sear or notch 334 in hammer body 318 to hold the trigger assembly in a cocked position, ready to fire. Disconnector 294 inhibits automatic operation of the firearm. Upon action of the discharge, hammer body 318 returns to a cocked position or ready to fire. However, hammer arm 326 momentarily engages with locking neck 296 to inhibit automatic operation. Once edge 344 engages with sear 334 and trigger pull 284 returns to the ready to fire position, hammer arm 326 disengages with locking neck 296 for a subsequent trigger pull to fire the weapon again, i.e., semi-automatic operation.

Pulling trigger pull 284 in the direction of arrow 328 causes a pressure contact between trigger body 294 and sear 334, i.e., hitting the wall, followed by releasing sear 334 from edge 344 of trigger body 294, i.e., breaking the wall. Once released, hammer body 318 rotates back in the direction of arrow 330 under tension of hammer spring 322 so that surface 332 of hammer body 318 strike the firing pin (not shown). Trigger limit set screw 340 and hammer limit set screw 342 limit the motion of trigger pull 284 and trigger body 280, as discussed infra.

FIG. 3f illustrates a side view of trigger body 280 with trigger pull 284, trigger shaft 286, notch 288, safety selector concave surface 290, opening 300 for disconnector spring 298, and opening 312 for trigger pull spring 310 and trigger pull adjustment screw 314. Notch 346 accepts a portion of hammer body 318. Rounded slot 299 accepts matching rounded bar 297 from disconnector body 280. Edge 344 of trigger body 280 is adapted to latchably engage with sear 334 of hammer body 318 to hold the hammer body in a cocked position or ready to fire.

In FIG. 3g , trigger assembly 232 is disposed within trigger housing 230 with trigger body 280 located within slots 236 and 244, and trigger pull 284 extending through rectangular opening 250. Pin 350 is disposed through opening 266 of trigger housing 230 and trigger shaft 286 to provide rotational movement of trigger body 280 upon pulling trigger pull 284. Pin 352 is disposed through opening 268 of trigger housing 230 and hammer shaft 320 to provide rotational movement of hammer body 318. Trigger limit set screw 340 is threaded into opening 260. Trigger limit set screw 342 is threaded into opening 262. Hammer limit set screw 340 and hammer limit set screw 342 are driven from the outside of trigger housing 232 toward the inside of the trigger housing.

FIG. 3h illustrates another view of trigger assembly 232 disposed within trigger housing 230 with trigger body 280 located within slots 236 and 244, and trigger pull 284 extending through rectangular opening 250. Pin 350 is disposed through opening 266 of trigger housing 230 and trigger shaft 286 to provide rotational movement of trigger body 280 upon pulling trigger pull 284. Pin 352 is disposed through opening 268 of trigger housing 230 and hammer shaft 320 to provide rotational movement of hammer body 318. Trigger limit set screw 340 is threaded into opening 260. Hammer limit set screw 342 is threaded into opening 262. Trigger limit set screw 340 and hammer limit set screw 342 are driven from the outside of trigger housing 232 toward the inside of the trigger housing.

FIG. 3i illustrates another view of trigger assembly 232 disposed within trigger housing 230 with trigger body 280 located within slots 236 and 244, and trigger pull 284 extending through rectangular opening 250. Pin 350 is disposed through opening 266 of trigger housing 230 and trigger shaft 286 to provide rotational movement of trigger body 280 upon pulling trigger pull 284. In FIG. 3j , trigger limit set screw 340 is threaded into opening 260 and disposed to be capable of contacting bottom surface 360 of trigger body 280.

FIG. 3k illustrates another view of trigger assembly 232 disposed within trigger housing 230 with trigger body 280 located within slots 236 and 244, and trigger pull 284 extending through rectangular opening 250. Pin 352 is disposed through opening 268 of trigger housing 230 and hammer shaft 320 to provide rotational movement of hammer body 318. In FIG. 3 l, hammer limit set screw 342 is threaded into opening 262 and disposed to be capable of contacting bottom surface 362 of trigger body 280.

FIG. 3m illustrates another view of trigger assembly 232 disposed within trigger housing 230 with trigger body 280 located within slots 236 and 244, and trigger pull 284 extending through rectangular opening 250. Pin 350 is disposed through opening 266 of trigger housing 230 and trigger shaft 286 to provide rotational movement of trigger body 280 upon pulling trigger pull 284. Pin 352 is disposed through opening 268 of trigger housing 230 and hammer shaft 320 to provide rotational movement of hammer body 318. Trigger limit set screw 340 is threaded into opening 260 and disposed to be capable of contacting bottom surface 360 of trigger body 280. Trigger limit set screw 342 is threaded into opening 262 and disposed to be capable of contacting bottom surface 362 of trigger body 280.

FIG. 3n illustrates another view of trigger assembly 232 disposed within trigger housing 230 with trigger body 280 located within slots 236 and 244, and trigger pull 284 extending through rectangular opening 250. Pin 350 is disposed through opening 266 of trigger housing 230 and trigger shaft 286 to provide rotational movement of trigger body 280 upon pulling trigger pull 284. Pin 352 is disposed through opening 268 of trigger housing 230 and hammer shaft 320 to provide rotational movement of hammer body 318. Trigger limit set screw 340 is threaded into opening 260 and disposed to be capable of contacting bottom surface 360 of trigger body 280. Trigger limit set screw 342 is threaded into opening 262 and disposed to be capable of contacting bottom surface 362 of trigger body 280.

Trigger limit set screw 340 and hammer limit set screw 342 are set to minimize the travel of trigger pull 284, and correspondingly the movement of trigger body 280. Upon trigger pull, trigger body 280 must exhibit some movement, i.e., creep travel, in order to pull edge 344 from sear 334 and release hammer body 318. Trigger limit set screw 340 sets the starting point of trigger pull 284 to reduce or eliminate pre-travel. Hammer limit set screw 342 limits the travel of trigger pull 284 in the direction of arrow 368 to reduce or eliminate post-travel. In one embodiment, trigger limit set screw 340 is adjusted first to set the screw as close to the wall of hammer release as possible. Again, trigger limit set screw is positioned to have a small positive movement of trigger pull 284, i.e., only creep travel, to reach the wall or release point of sear 334. On the other hand, trigger limit set screw should not be set too close to the wall for unintended discharge of the weapon. In one embodiment, the creep travel of trigger pull 284 to release hammer body 318 is 1.0 degrees with 3-6 pound trigger pull. Pre-trigger pull, trigger limit set screw 340 contacts surface 360 of trigger body 280, as shown in FIG. 3m . Hammer limit set screw 342 is initially separated from surface 360 of trigger body 280. Hammer limit set screw 342 is adjusted second to set the screw as close to the post release of hammer body 318. Upon trigger pull, trigger pull 284 and trigger body 280 exhibit creep travel, i.e., the minimum travel required to release sear 334. Post trigger pull, hammer limit set screw 342 contacts surface 362 of trigger body 280 stop further post travel, as shown in FIG. 3n . Trigger limit set screw 340 is slightly separated from surface 360 of trigger body 280. Accordingly, trigger limit set screw 340 and hammer limit set screw 342 reduce the travel of trigger pull 284 in the forward and backward directions to a minimum distance needed to release sear 334. Trigger limit set screw 340 and hammer limit set screw 342 eliminate unnecessary travel of trigger pull 284, i.e., pre-travel by setting the trigger starting point and post-travel in the direction of arrow 368, leaving only the creep travel necessary to release the hammer to hit the fire pin. Trigger limit set screw 340 and hammer limit set screw 342 make sporting rifle 200 safer to operate and more accurate and reliable.

Trigger limit set screw 340 and hammer limit set screw 342 operate as limit stops to physically stop undesired movement of trigger pull 284 and reduce or eliminate pre-travel and post-travel. The physical limit stop is achieved with the metal-to-metal contact between trigger limit set screw 340 and surface 360 of trigger body 280 and the metal-to-metal contact between hammer limit set screw 342 and surface 362 of trigger body 280. The stop position of trigger limit set screw 340 and hammer limit set screw 342 can be tuned by adjusting the height of the set screws extending from threaded openings 260 and 262 of trigger housing 230 to provide only creep travel for trigger pull 288 and eliminate pre-travel and post-travel, for any trigger poundage. Accordingly, pre-travel and post-travel can be eliminated without down-scaling trigger poundage, as used in the prior art.

Other types of limit stops, providing a similar function as trigger limit set screw 340 and hammer limit set screw 342, can be used to reduce or eliminate pre-travel and post-travel. For example, solid shafts or posts 367 and 369, as shown in FIG. 4, can be inserted through non-threaded openings 260 and 262 and sealed or locked in place to set the proper distance between the top of the solid shafts and surfaces 360 and 362 of trigger body 280 to tune or calibrate to the desired limit stop for sporting rifle 200. In another embodiment, solid shafts or posts 367 and 369 extend from trigger housing 230 at fixed distances between the top of the solid shafts and surfaces 360 and 362 of trigger body 280 to set to the desired limit stop for sporting rifle 200. Solid shafts 367 and 369 function as limit stops, similar to trigger limit set screw 340 and hammer limit set screw 342, as described in FIGS. 3m -3 n. The limit stop trigger assembly 208 is applicable to virtually all types of weapons with a trigger release, including long guns, hand guns, cross-bows, bolt action, semi-automatic, automatic, and military launchers.

FIGS. 5a-5e illustrate the operation of safety selector 370 working in conjunction with trigger assembly 232. In FIG. 5a , notch 288 of trigger body 280 has a concave surface 290 configured to accept safety selector 370. FIG. 5b shows a first position of safety selector 370 with curved surface 372 at least partially within concave surface 290. In the first position of safety selector 370, trigger body 280 and trigger pull 284 are prevented from moving by nature of curved surface 372 at least partially within concave surface 290. The safety for sporting rifle 200 is active preventing the weapon from firing even if pressure is applied to trigger pull 284. FIG. 5c shows a second position of safety selector 370 with curved surface 372 still at least partially within concave surface 290. In the second position of safety selector 370, trigger body 280 and trigger pull 284 are prevented from moving by nature of curved surface 372 at least partially within concave surface 290. The safety for sporting rifle 200 remains active preventing the weapon from firing even if pressure is applied to trigger pull 284. FIG. 5d shows a third position of safety selector 370 with curved surface 372 still at least partially within concave surface 290. In the third position of safety selector 370, trigger body 280 and trigger pull 284 are prevented from moving by nature of curved surface 372 at least partially within concave surface 290. The safety for sporting rifle 200 remains active preventing the weapon from firing even if pressure is applied to trigger pull 284. FIG. 5e shows a fourth position of safety selector 370 with straight surface 374 over concave surface 290. In the fourth position of safety selector 370, trigger body 280 and trigger pull 284 are now free to move because curved surface 372 is no longer at least partially within concave surface 290. The safety for sporting rifle 200 is deactivated and the weapon will fire if there is a round in the chamber, hammer body 318 is loaded, and pressure is applied to trigger pull 284.

While one or more embodiments have been illustrated and described in detail, the skilled artisan will appreciate that modifications and adaptations to those embodiments may be made without departing from the scope of the present disclosure. 

What is claimed:
 1. A firearm trigger assembly, comprising: a trigger housing including a first opening and second opening through a surface of the trigger housing; a trigger assembly disposed partially within the trigger housing; a first limit stop disposed through the first opening to limit movement of the trigger assembly in a first direction; and a second limit stop disposed through the second opening to limit movement of the trigger assembly in a second direction.
 2. The firearm trigger assembly of claim 1, wherein the trigger assembly includes: a trigger body with a trigger pull disposed within the trigger housing; a disconnector in contact with the trigger body; and a hammer body rotationally connected to the trigger body and latchable to the trigger body.
 3. The firearm trigger assembly of claim 1, wherein the trigger pull extends through a third opening in the trigger housing between the first opening and second opening.
 4. The firearm trigger assembly of claim 1, wherein the first limit stop contacts a first portion of a surface of the trigger body to stop movement of the trigger assembly in the first direction and the second limit stop contacts a second portion of the surface of the trigger body to stop movement of the trigger assembly in the second direction.
 5. The firearm trigger assembly of claim 1, wherein the first limit stop includes a first set screw threaded through the first opening and the second limit stop includes a second set screw threaded through the second opening.
 6. The firearm trigger assembly of claim 1, wherein the trigger body includes a concave surface adapted to receive a safety selector.
 7. A firearm trigger assembly, comprising: a trigger housing; a trigger assembly disposed partially within the trigger housing; and a first limit stop disposed through a first opening of the trigger housing to limit movement of the trigger assembly in a first direction.
 8. The firearm trigger assembly of claim 7, further including a second limit stop disposed through a second opening in the trigger housing to limit movement of the trigger assembly in a second direction.
 9. The firearm trigger assembly of claim 8, wherein the trigger assembly includes: a trigger body with a trigger pull disposed within the trigger housing; a disconnector in contact with the trigger body; and a hammer body rotationally connected to the trigger body and latchable to the trigger body.
 10. The firearm trigger assembly of claim 9, wherein the trigger pull extends through a third opening in the trigger housing between the first opening and second opening.
 11. The firearm trigger assembly of claim 9, wherein the trigger body includes a concave surface.
 12. The firearm trigger assembly of claim 8, wherein the first limit stop contacts a first portion of a surface of the trigger body to stop movement of the trigger assembly in the first direction and the second limit stop contacts a second portion of the surface of the trigger body to stop movement of the trigger assembly in the second direction.
 13. The firearm trigger assembly of claim 8, wherein the first limit stop includes a first set screw threaded through the first opening and the second limit stop includes a second set screw threaded through the second opening.
 14. A method of making a firearm trigger assembly, comprising: providing a trigger housing; disposing a trigger assembly partially within the trigger housing; and disposing a first limit stop through a first opening of the trigger housing to limit movement of the trigger assembly in a first direction.
 15. The method of claim 14, further including disposing a second limit stop through a second opening in the trigger housing to limit movement of the trigger assembly in a second direction.
 16. The method of claim 15, wherein disposing the trigger assembly includes: disposing a trigger body with a trigger pull within the trigger housing; providing a disconnector in contact with the trigger body; and providing a hammer body rotationally connected to the trigger body and latchable to the trigger body.
 17. The method of claim 16, wherein the trigger pull extends through a third opening in the trigger housing between the first opening and second opening.
 18. The method of claim 16, wherein the trigger body includes a concave surface.
 19. The method of claim 15, wherein the first limit stop contacts a first portion of a surface of the trigger body to stop movement of the trigger assembly in the first direction and the second limit stop contacts a second portion of the surface of the trigger body to stop movement of the trigger assembly in the second direction.
 20. The method of claim 15, wherein the first limit stop includes a first set screw threaded through the first opening and the second limit stop includes a second set screw threaded through the second opening. 